Views: 0 Author: Site Editor Publish Time: 2022-06-03 Origin: Site
According to an article recently published by the internationally renowned technology media "Nature", a study of more than 30,000 health care workers in Qatar found that the flu vaccine may be able to prevent the new crown virus, especially in severe new crown protection.
However, it is not clear why, or how long the flu vaccine's protection against the new coronavirus will last. People who have been vaccinated against the flu are nearly 90 percent less likely to become severely ill with the new coronavirus in the following months, compared with people who have not been recently vaccinated, the study showed.
Influenza vaccine has a significant effect on severe protection against new crowns
In the first few months after the outbreak of the new crown, because the new crown vaccine was still in development, researchers were very interested in the possibility of existing vaccines for other diseases against the new crown virus. But because each person may receive several different vaccines at the same time, this makes it difficult to judge the effectiveness of a particular vaccine.
To minimise the impact of this "health user effect", a team led by Laith Jamal Abu-Raddad, an infectious disease epidemiologist at Weill Cornell Medical College in Qatar, analysed 30,774 health workers in the country in 2020. Health records between September 17, 2020 and December 31, 2020 (after the flu vaccine and the period before the Covid-19 vaccine). Abu-Raddad argues that health-care workers may have smaller differences in health-related behaviors than the general population, which could reduce (but probably not eliminate) bias.
The study found that compared with health care workers who had not received the flu vaccine, health care workers who had been
vaccinated against the flu were 30% less likely to test positive for COVID-19 and 89% less likely to develop severe disease during the same period (although The absolute number of patients who developed severe Covid-19 was low in both groups). The team of epidemiologist Günther Fink of the University of Basel in Switzerland also previously reported that the flu vaccine was associated with a lower risk of death in hospitalized patients with the new crown in Brazil. According to Günther Fink, the Qatar analysis reduces the possibility that other studies finding the same link are chance. "This is an important piece of evidence," said Mihai Netea, an infectious disease specialist at the University Medical Center in Nijmegen, the Netherlands. The observation that the flu vaccine is not only associated with a reduction in Covid-19 infections but also a reduction in severe Covid-19 disease strongly suggests that , this protective effect is real.
The cause and effect of the influenza vaccine against the new crown is still unclear
However, it is unclear how long the flu vaccine's protective effect against the new coronavirus will last. In the Qatar study, Abu-Raddad's team recorded an average interval of about six weeks between vaccination and contracting the virus among people who contracted the new coronavirus after receiving the flu shot.
Mihai Netea also said: "I don't expect this effect to last too long." He speculated that the protective effect of the flu vaccine against the new crown virus may last 6 months to 2 years. In addition, scientists are not entirely clear why influenza vaccines composed of inactivated influenza viruses also protect against new coronaviruses.
Netea speculates that flu vaccines not only train the immune system to recognize specific pathogens, but also strengthen broad antiviral defenses. Netea has seen signs of this reaction in flu vaccine recipients. Currently, Netea's team is also working to quantify the effectiveness of vaccines against the new coronavirus against influenza and other diseases.
His team is now launching a randomized, placebo-controlled trial in Brazil that will test whether the flu and measles-mumps-rubella vaccines protect against Covid-19. Netea believes that knowing that vaccines for influenza and other diseases can provide protection against the new coronavirus, even if only partially, for a limited time, can limit the damage caused by future new coronavirus outbreaks before a vaccine against the disease is developed.
What are the similarities and differences between influenza virus and new coronavirus?
Viruses are acellular organisms that parasitize within living cells and multiply by replication. Different viruses invade cells in different ways, but most of them need to achieve cellular internalization by binding to specific receptor proteins or lipid structures on the cell surface, thereby initiating the invasion program and infecting host cells. Therefore, revealing the specific process and mechanism of virus binding and internalization to invade cells will help to develop targeted drugs or vaccines from the source.
According to the antigenicity of nucleoprotein, influenza virus can be divided into four types: A (A), B (B), C (C), and D (D). Human influenza is mainly caused by influenza A and B viruses, influenza C virus only causes insignificant or mild upper respiratory tract infection in humans, and the host of influenza D virus is mainly cattle. Influenza virus belongs to the family Orthomyxoviridae and is an enveloped virus with three types of membrane proteins embedded in its membrane: Hemagglutinin (HA), Neuraminidase (NA) and Membrane protein 2 (Membrane protein 2). , M2). HA exists in the form of homotrimers.
HA is hydrolyzed to form two parts, the light chain and the heavy chain. The heavy chain is responsible for the binding of the virus to the cell, while the light chain assists in the semi-fusion of the viral membrane and the endosome membrane. NA is a mushroom-shaped tetrameric glycoprotein that has the activity of hydrolyzing sialic acid, which helps the virus to be released from the host cell. Membrane protein M2 functions as an ion channel and regulates pH within the membrane. In addition, the matrix protein M1 constitutes the shell skeleton of the virus, which is closely combined with the outermost envelope of the virus, and plays a role in protecting the virus core and maintaining the virus spatial structure. The genetic material of a virus is a viral ribonucleoprotein complex formed by folding together a single-stranded negative-stranded RNA and a nucleoprotein (Figure 4).
Figure 4 Influenza virus structure and shape
Coronaviruses are a large group of viruses that exist widely in nature, infect only vertebrates, and were first isolated from chickens. The diameter of coronavirus particles is about 60-220 nm, and there are 3 glycoproteins on the surface: spike glycoprotein, small envelope glycoprotein, membrane glycoprotein, and a few also contain hemagglutinin glycoprotein (Figure 5). The nucleic acid of coronavirus is a linear single-stranded positive-stranded RNA with a methylated cap structure at the 5' end and a polyA tail at the 3' end, similar to eukaryotic mRNA, and can play the role of a translation template by itself. The full length of the genome is 27-32 kb, is the virus with the largest genome among the known RNA viruses.
The International Committee on Taxonomy of Viruses classified it into 4 genera, namely alpha, beta, gamma and the new putative deltacoronavirus. The new coronavirus is a beta coronavirus with strong infectivity. The whole genome sequence of the new coronavirus and the protein that the virus binds to cells have been detected, but the mechanism by which it invades and infects cells is still unclear.
Picture Figure 5 The structure and transmission electron microscope image of the new coronavirus (Source: [3])
Both influenza virus and SARS-CoV-2 are adsorbed to the cell surface through the binding of ligand receptors, and the HA and S proteins are activated by the action of intracellular proteolytic enzymes to form two subunits, which are responsible for the virus and the host cell respectively. binding and mediating the membrane fusion process. After influenza virus binds to cellular receptors, it requires the participation of various cytokines to achieve endocytosis, and studies have shown that the new coronavirus may also use certain intracellular pro-adsorption factors, such as binding to cellular glycoproteins, to enhance its infection sex.
Influenza virus and new coronavirus have some similarities in the mechanism of their action on cells, so using the research method of influenza virus to carry out research on the effect of new coronavirus and cells is a potential way, and the protection of influenza vaccine against new crown is not difficult understand.
